Angle plug



Patented July 26, 1927.

UNITED STATES PATENT OFFICE.`

THOMAS J. xnnwIN, or CHICAGO, ILLINCIS, AssIGNoR, BY MESNE ASSIGNMENTS,To

CHICAGO ELECTRIC MANUFACTURING COMPANY, or CHICAGO, ILLI'NoIs, A CCR-roIiATIoN or ILLINOIS.

ANGLE PLUG.

Application inea January 3, 1921. serial No. 434,733.

My invention relates to the class of electric fittings commonly known asattachment plugs and used for affording a detachable circuit connectionto a socket for an electric lampv or the like. Generally speaking, myinvention aims to provide a cheaply constructed, strong and good lookingfitting of this kind which will be easy to wire, which can readily beused to good advantage with wires coming from a direction angular to theaxis of the socket, which will afford strong mechanical protection aswell as weather-proof protection for the point of afttaclnnent of thewire, and which wil-l readily relieve such connection of any strain onthe wire.

In one of its more particular aspects, my invention aims to provide anattachment plug` of this kind having a metallic casing so designed asnot only to house the insulating body which carries the wire terminal orterminals, but also completely to hou-se the joint between the wire andsuch terminal or terminals, and having a portion of this casing disposedfor relieving these terminals of any strains on the wire. Furthermore7 Iaim to provide exceedingly simple and effective means for attaching thewire; to provide simple means for holding the insulating body whichsupports the wire terminal or terminals, and for permitting a readyconnecting of the wires to the same; to provide a casing so arranged asto facilitate' this wiring even when the wire comes from a genn eraldirection at right angles to the axis of the socket with whichthe plugis-tobe used, andv to provide simple means for mechantcally protectingthe resulting. joint or con-` nection. provide an attachment plug withai casing having its main portion formed from a` single'piece ofdie castmetal and havingy aseparable cap so arranged: as to take thrust 0E theconnection to the wire, and alsoarranged so that it can be used withequal facility with metal-sheathedl wire. Still further and moredetailed objects will appear from the following specification andfromthe accompanying drawings, in which Fig. l is a side4 elevation of asingle pole anglespl'ug embodying my invention, to gether with a sectionof the rear end of a lamp socket interlocked with this plug.-

Moreover, my invention aims to- Fig. 2 is a section through the sameangle plug, taken along the medial plane of the angle and showing thecap of the plug as engaging a wrapping of tape on the wire.

Fig. 3 is a similar section through a donbl'e-pole angle plu-g, showingvthe cap as engaging a knot in the two wires. v

Y F ig. 4 is a transverse section through Fig. 2 along thecorrespondingly numbered line of that figure.

Fig. 5 is a reduced section through the main metal portion of Fig. 2showing the disposi-` tion of the wire before the same is attached tothe wire terminal, and also showing this metal elbow as equipped withcross-pins at right angles to the medial plane of the angle plug.

Fig. 6 is a fragmentary horizontal section taken along the line 6 6. ofFig. 2.

Fig. 7 is a perspective view of the wire terminal. i

lVhere the wire or wires which are to connect to an attachment plug comefrom a direction substantially at right angles to the axis of the socketwith which the plug is tio be used, it has heretofore been customary toconstruct angle plugs (sometimes also known as elbow plugs) with thewire terminal andA contact terminal portions carriedby a tubular elbowmolded of insulating ina-1 terial and to conceal the attachment of thewire or wires by a cap threaded upon this insulating body. Owing to thenature of the insulating compounds generally used for such purposes, theresulting plugs have proven tool brittle to stand knocks, and too easilysoftened to retain a firm grip in hot weather on the imbedded pins whichinterlock such plugs with the lamp sockets. Nor has-the angular shape ofthe insulation lent itself to the employment of a' metal shell such aswould be highly desirable where fittings of this kind are likely to besubjected to rough treatment, as in the case of connector' plugs for usewith the electric head'glamps on Ford automobiles. Moreover, theattaching of-a wire wit-hin a tubular elbow is difficult to performywith the proper firmness for preventing a strain on the wire fromsevering the connection vor possibly rupturing the wire at its point ofattachment.

Tov overcomeV all of these difliculties7 my invention aims to provideconnector plugs employing tubular metal elbows which will alord thedesired mechanical protection, and to provid-e an elbow-shaped metalcasing which can readily be made of a die casting; to provide theinsulating portion in a relatively small .torni which can readily bemachined out ot hard rubber, thereby permitting of a less fragile torniot insulation than that ordinarily obtainable in a molded composition;to provide a simple and ineX- pensive torni ot wire terminal which canreadily be attached to suoli a cheaply manufactured insulating part andwhich will et- 'fectively anchor the wire without appreciably weakening`the latter; to arrange the parts so that the wire can readily beattached to the terminal while the latter is disposed outside oit thetubular elbow; to providesirnple means tor causingl a retraction of thewire to seat the insulating body tirmly in the elbow; and to providesimple and effective means for preventing an excessive retraction oitthe wire aiter it has thus drawn the` insulator' to its seated posiAtion. Furthermore, my invention aims to provide a connector plug of thecl described which will readily lend itselt to both single-pole anddouble-pole constructions and which will readily pred-etermine themedial plane ot the elbow when the plug` is in use.

ln their immediate commercial aspects, the connector plugs otl myinvention are particularly suited tor use in connection Y-yithautoinobile lamps carried by sorkets having their shells equipped Aforinterlockingl with laterally projecting pins on tl e plugs and havingspring-pressed contact elements adapted to engage the wire terminals outhe plugs when the latter are thus interlocked with the shells ot thesock-k l ain therefore illustrating and deseribino' the connector plugsof my invention in 2liornis adapte Vl i'or these purposes, although donot wish to be limited to any particular uses of the same. v

Referring tirst to the connector plug ot' Figs. l, 2 and fl, theseligures show an angle Y plug designed lor use with a lamp socket havinga cylindrical shell l equipped near its end with diametrically oppositebayonet slots adapted to engage lateral pins 2 projecting trom the angleplug. The socket shell l houses the usual insulating' body f3 supportinga springpressed plunger et which is disposed axially oi the casing 1 andis continuously urged by the spring associated with-ittowards the rearend ot the socket shell,V atter'the general manner of the plunger shownin U. S. Pat-entNo. 1.083542 ot January 6, 1914i to George C. Knanft'.To cooperate with the plunger 4 which :terms parts ot the connectionwithin the socket to the lamp, I provide a screw 5 which extends throughan axial bore in a cylindrical insulator 6 and which is threaded intothe shank 7 ot a wire terminal equipped at its rear end with a loop 8through which the tip portion of the corresponding wire 9 is adapted tobe hooked. The threaded shank '4" of vthe wir-e terminal is slidablydisposed in a bore ot larger diam` eter than the shank ot the screw 5and eX- tending into the insulator G 'troni the rear ot the latter-,sothat upon tightening the screw 5 the shank 7 will be drawn torwardly otthe insulator and will therefore double the tip 9 ot the wire into aloop and draw this tip into the borel() within which the shank 7 isslidably disposed. In so doing, the screw kinks the wir-e into ananchoring loop bet'ore the tip ot' the screw engages the wire and clampsthe latter against the rear part ot' the loo-p S.

The insulator 6 in turn is merely sl'ldabl-e in the 'forward end ot themetal elbow ll, vwhich elbow is desirably oit' diecast metal anddesirably has the anchoring pins 2 cast upon the same. This elbow hasits bore contracted to 'form an interior annular shoulder 13 spaced fromthe forward end ot' the elbow by a distance shorter than the length otthe insulator 6, so that the entry ot' this insulator into the elbowwill be limited by this shoulder to a position in which the Aforward endportion ot the insulator 6 projects beyond the torward end ot' theelbow. Moreover, the inet-al elbow also desirably has int-egralwvith ita web lll extending longitudinally along its interior ttor some distancetoi-ward ot' the said shoulder l2', and adapted to enter a correspendinglongitudinal recess ou the surface oi the insulator (S after the mannershown in Figs. 2 and 4, so as to prevent the i.n sulator troni rotrtinn`within the bore ot the elbow. The rear end ot the elbow, which end inthe illustrated embodinuint extends atright angles to the forward end,dcsirablv is threaded on its exterior'to tit a cap lb 'tor the purposeshereafter desruibed. A

l/Viththe parts thus arranged, the cap l5 is first left off the elbowbut slipped over the free end ot' the wire, while the insulator 6together with the wire terminal carried by the latter are lel't out ofthe metal elbow. Then the wire l1 is slid through this elbow after themanner shown in Fig. 3, which can readily be done while imparting arelatively slight curve to the wire, and this wire is attached to thewire terminal after the manner shown in Fig. 2. Then the wire is pulledback, and the insulator 6 is slid into the forward end of the metalelbow during this retracting of the wire until the insulator engagesboth the web 14 and the annulaishoulder 13. After this has been done,the cap 15 can be brought up from its previous loose position of-Fig. 5and can readily be screwed upon the rear end of the elbow so as toafford a handsome finish for this end, while also providing means forsecuring the metal of the elbow tightly to a metal sheath 16 on the wireif the wire was metal sheathed. In either case, I also desirably employthis cap for relieving the wire of any strains which might tend to pullits tip out of the fastening of the latter` to the wire terminal, suchas a downward pull on the wire in Fig. 2. For this purpose, I may simplywrap the wire adjacent to the rear end of the elbow with a few layers oftape 17, thereby providing an enlargement of greater diameter than thatof the bore of the cap l5, so that the contracted tail end of this capwill engage the tape when the cap is screwed into position (as shown inFig. 2) and thereby will relieve the wire of undue strains.

With the parts thus arranged and assembled, it will be obvious that themetal shell of the installed plug will afford a strong mechanicalprotection; that the general arrangement will facilitate the wiring, andthat the ability to attach the wire to this terminal while the latter isout of the elbow will insure the making of a connection which will beboth mechanically and electrically ample. Moreover, the position of thean choring pins 2 with respect to the medial plane of the elbow willreadily determine the position of the plug when used in connection witha lamp-socket having bayonet catch formations in any given position. Forexample, if the socket has its axis horizontal and has its bayonet catchformations in a vertical plane through that axis, and the angle plughaving its anchoring pins in the medial plane of the elbow will presentits rear end in a vertical position after the manner of Fig. l.

However, while I have heretofore described the connector plug of myinvention in a single-pole embodiment and have illustrated the same asincluding a rightangled elbow, I do not wish to be limited to these orother details of the construction and ar- 2. So also, the relativeposition of the crosspins 2 might be altered, as for example after themanner indicated in dotted lines in Fig. 3 which shows an elbow designedfor use at right angles tothe position of Fig. 1.

I claim as my invention:

In an electric fitting, an elbow-shaped casing having its forward armcounterbored to provideV an inner annular shoulder spaced from the mouthof the said arm and having a iin projecting radially inward into thesaid counterbored portion adjacent to the said shoulder, the shoulderbeing disposed forwardly of the bend of the casing; a tubular insulatorsocketed in the said counterbored arm and abutting at its rear endagainst the said shoulder and having a notch fitted over the said fin toprevent the insulator from rotating in the said arm, the forward part ofthe bore of the insulator being contracted in diameter; a wire terminalmember slidably inserted in the insulator bore from the rear of theinsulator and having a forward threaded end and presenting an eyeadjacent to the rear end of the insulator; a screw eX- tending throughthe contracted bore portion of the insulator and having its headengaging the forward end of the insulator and its shank threaded intothe said threaded end of the wire terminal member; and an insulatedcircuit wire extending into the casing through the other arm of thecasing and having a bared end extending through the eye of the terminalmember and clamped against and kinked into the rear end of the insulatorbore. v

Signed at Chicago, Illinois, December Y THOMAS J. KERWIN.

